The civil construction is thought to be one of the most productive industries for the economic and social development of a region. However, environmental impacts resulting from the consumption of natural resources or the generation of waste are a contemporary problem, and there must be a balance among them, as a way of not compromising environmental sustainability [1].

The introduction of new materials in civil construction led to relevant technological advances, especially with the increased use of plastic materials. Civil construction supply chain accounts for 20% of plastic material consumed in the world, being the second most important industry, after packaging [2]. Taking into account that part of such consumption is transformed into waste in urban areas, the relevance of civil construction is considerable. Thus, studies to reuse these materials or other waste in components of building products or systems are needed.

A viable alternative to incorporate polymeric waste is to use it for lightweight concrete, which, besides not overloading structures, has mechanical impact properties in flooring systems and consequent impact sound reduction in the lower pavement [3,4].

The use of polymeric waste in cementitious composites is the object of researches whose focus restricts to properties regarding the use as a fiber; however, the incorporated quantity is reduced, if compared to the use of polymer in the form of grains or aggregates. [5] complement that the disadvantage of adding polymers to cementitious matrixes is that it represents a reduction of mechanical properties and an increase of the elasticity module, leading to more deformations. Nonetheless, it presents an improvement in thermal insulation and in acoustic performance [4]. Recent results also point out the need of new studies to assess granular polymeric waste incorporated to cementitious-base matrixes.

It is known that the use of ethylene vinyl acetate (EVA) in concrete, as a substitute to the use of conventional aggregates, brings air incorporation through the component own porosity. [6] states this solution turns into an efficient method to provide concrete with acoustic insulation.

EVA is one of the main inputs in the leather-footwear industry, used to produce soles for shoes. This material is supplied in reduced thickness boards and variable widths. For footwear production these boards are cut off, which generates leftovers, leading to disposal costs for the company that generated the waste and also to environmental impacts.

The Brazilian civil construction industry is adapting to ABNT NBR 15575: 2013 [7]- Performance Standard. Such normative specifies, through qualitative requirements and quantitative criteria, the acoustic, thermal & structural performance, durability and fire resistance requirements, among others. The sector investigates alternatives to comply with acoustic performance requirements for buildings, with competitive solutions that allow for the proper disposal of waste coming from other industries.

In this scenario, added to the need of using polymeric waste, the goal of this study is to analyze different EVA solid ratios and grain sizes in the development of lightweight concrete subfloor slabs, in order to mitigate the impact sound in flooring systems, with two types of replacements, one with the coarse aggregate replacement and the other with total replacement, both of coarse and fine aggregate.

Polymers may be defined as substances composed of macromolecules formed out of the same structural unit, called monomer, repeated several times, and connected among them covalently [8]. The EVA polymer is composed of a high technology mix of ethyl, vinyl and acetate, with the mechanical behavior of an elastomer, and reversible elongation in a long strip of deformation at room temperature [1].

The insulation of impact sound in overlapping rooms receives an efficient treatment through floating floors, composed of a resilient base among two rigid plates, floor slab and coating. These flooring systems use resonance and damping concepts to reduce vibration in the rigid base and increase the acoustic insulation [9], and this principle is broadly used in independent layers systems. However, this same principle can also be met with the incorporation of resilient materials in cementitious mixes. According to [10], materials used for this purposes are based on polymers, which allow broad reuse and recycling possibilities.

These materials promote a mass reduction in flooring systems and are susceptible to deformations, which may lead to changes in the damping capacity over time. This approach was investigated by [11], who found differences in the mechanical impact damping capacity, with high damping losses in fibrous materials in open-cell materials, comparatively to closed-cell materials. Besides, [12] points out that different types of resilient materials used in vibration damping show different behaviors due to sound frequency, such as cork, cork-based composites, felt, polymeric foams and elastomers, which may be used in the form of liners or plates, in high frequencies, for which the static deflections are reduced.

All of these materials have part of their elasticity determined by the way the air behaves when the material is compressed. Low density, open-cell materials may have deformations due to permanent compression, besides presenting wear and tear problems in the coating joints. On the other hand, closed-cell materials show a pneumatic effect caused by air contained in its interior [11,13].

According to [15], the use of resilient bases in buildings has certain specificities, when compared to the use in isolated equipment. Impact sound insulation must provide bases that are rigid enough to assure stability during the use of flooring system; however, they will have their insulation capacity reduced when compared to softer materials. Thus, acoustic and mechanical properties for these materials must be equally considered [13].

In this sense, studies proposing compounds with cement, natural aggregate and/or light aggregates have been designed to characterize and analyze the technical viability of different types of mixes. Differences caused by a higher water absorption in lightweight aggregates are indicated as the main concern in the proposal of new cementitious materials and more specific tests to characterize these aggregates are still in a discussion [15] Especially for the use in flooring systems with concrete slab, studies about the influence of lightweight aggregates porosity [15, 16], the type of light aggregate used [17,18], and of polymeric waste grain size [4]; indicate that the adequate characterization of these aggregates may determine the control on the flooring system acoustic performance regarding impact sound.

Concerning flooring systems requirements, ABNT NBR 15575 (2013) [7] sets performance acoustic levels, as minimum (M), intermediary (I) and superior (S), according to Table 1. These requirements must be met in all housing buildings.

Table 1

Source: ABNT NBR 15575:2013

Table 2

Source: The authors

Table 3

Source: The authors

The experimental program included the aggregates characterization, concrete dosage, subfloor slabs molding and the impact sound test, with two types of replacement of natural aggregates for EVA. In the first stage, natural coarse aggregates (crushed stone) were replaced for EVA in the mix, in the equivalent grain size. In the second stage, the coarse aggregates replacement was maintained, besides partially (50%) replacing fine aggregates (sand) for EVA. The experimental program does not include mechanical tests, because the material developed is used only as a non-structural coating.

After assessing the samples, it is possible to conclude that:

The incorporation of EVA aggregates in concrete is an efficient way, with reduced cost, of incorporating air and reducing slabs specific mass, leading to a reduction of acoustic transmission of impact sound in flooring systems; thus, it was proposed the use of polymeric waste as a building element;